Page 135 - Basic Electrical Engineering

More problems using this method have been solved separately.

2.8 NETWORK THEOREMS
We described earlier the mesh current and nodal voltage analysis of circuit

problems. The procedure involves solving of number of equations depending
upon the complexity of the network. Many networks require only restricted

analysis, e.g., finding current through a particular resistor or finding the value
of load resistance at which maximum power will be transferred from the

source to the load. Certain circuit theorems have been developed to solve
such problems. For circuit solutions we will be using a particular theorem or

method depending upon which method will require less time in calculations.
The circuit theorems being discussed in this chapter are as follows:

1. Superposition theorem
2. Thevenin’s theorem
3. Norton’s theorem
4. Millman’s theorem
5. Maximum power transfer theorem

In addition, circuit simplification using the star-delta transformation method
has also been discussed with plenty of examples.

2.8.1 Superposition Theorem

An electrical circuit may contain more than one source of supply. The
sources of supply may be a voltage source or a current source. In solving of

circuit problems having multiple sources of supply, the effect of each source
is calculated separately and the combined effect of all the sources are taken

into consideration. This is the essence of the superposition theorem.
The superposition theorem states that in a linear network containing more

than one source, the current flowing in any branch is the algebraic sum of
currents that would have been produced by each source taken separately,